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Konus 130 Maksutov-Cassegrain - The Dollar Menu Mak The Konus Maksutov-Cassegrain is the third scope I've bought in a year, it's a 'cat' produced by Chinese optic manufacturer Bosma and sold under the Italian Konus label on a motorised equatorial mount as the Motormax 130HM, Celestron also sell a standalone optical tube as a spotting scope. The Konus version is commonly found on eBay and astromart at under $250 for the tube alone, in fact for a while it was so common that some people, myself included, began to speculate that it must posess some fundamental defect, the reputation of the Baytronix brand taints everything on eBay. I'm sure you've seen these and wondered whether they're really a bargain or not, well a combination of curiosity, necessity and plain old cheap-skate-ness prompted me to buy one and give it a whirl. Why Did I Buy Such A Scope? After a lengthy hiatus from astronomical activity I got interested in amateur astronomy last year, I was 'given' a 100mm F/6 Orion refractor as a Christmas present which has got a decent amount of use from my back yard over the last year. Given that I live in the middle of Oakland, just a stones throw from the Colloseum my visual observing has been confined to bright objects, leaving the details of faint fuzzies to the magic of CCD's and image processing. My refractor does a reasonable job on planets but to get that close up view I found myself stacking barlow lenses and using eyepieces with eye reliefs more commonly associated with contact lenses, or funneling that light into a webcam. Stacking those optics on the cheap Chinese focuser was far from ideal, and the blue meanies did their best to ruin my attempts at imaging the planets, so I began to feel that I should look at a scope more suited for planetary imaging. Why spend all that effort bending light to focus at 600mm only to spend more effort unbending it to reach a focal length nearer 2 metres? My existing 100mm f/6 Orion refractor, a great general purpose scope on a solid mount. My other Orion - he may be dressed as a space cadet but he's not into astronomy yet, he's one of the reasons why I'm pinching pennies and proud of it! Why Did I Choose an MCT?  So, the idea to acquire a Maksutov-Cassegrain scope came from a love of the planets, long focal lengths with 'apo-like' colour correction at prices that won't break the bank. And that last point was important since I'd just added another Orion to my household in June, he's 5 months old now and isn't so interested in astronomy just yet, he can see the moon, but since he can't put it in his mouth he loses interest pretty quickly. As astronomy gear goes, MCTs are generally pretty cheap, the simple design uses a spherical corrector lens and 2 spherical mirrors - the secondary can simply be a silvered area on the corrector lens. The simplicity of the design also limits the size of the scope, as the aperture increases the thickness of the primary corrector lens also increases and becomes heavier, beyond 150mm of aperture the Schmidt-Cassergrain design becomes a more popular choice with the thinner corrector plate making for a lighter tube and you'll find the big optics manufacturers tend to follow this pattern. In the 90-150mm range there are cheap offerings from every manufacturer with costs from $200-$600 but the real quality comes from Russian manufacturer Intes-Micro who make Monster-Maks with apertures of up to 400mm (it'll be no surprise to you that Dimitry Maksutov was Russian). I don't need anything so large, 130mm or thereabouts would give me enough extra aperture to exceed the light gathering of my refractor and I was spoiled for choice from the big three -  Meade's 125mm ETX, Orion's 127mm Apex, Celestron's C130, but being a cheapskate I was attracted to the Konus 130 which has been selling from reputable dealers on eBay and astromart. I picked up a lightly used OTA on astromart for $200, many dealers are selling the Konus scope with a motorised mount for about $500, and it appears that a lot of people are buying the package and later selling the scope. So you can pick up one of these on your favourite used gear site for a relatively small amount of cash, and if you're prepared to work around, or overlook, some issues then you'll get an excellent planetary scope for your small investment. The Real Costs of Saving Money Issues, yes there are a few, but underneath the rough edges there are decent optics that you can benefit from and in my case the benefit to my wallet is much appreciated. While it has the Konus name on the packaging it's made by the same Chinese manufacturer that produces the Celestron C130, if the words 'used' and 'Konus' don't instill confidence then you can pick up the Celestron scope new for $320 (still $80 cheaper than the Orion Apex), this might prove prudent since the scope doesn't exude an air of quality and I wouldn't be surprised if my good example is far from the norm. The bare tube, as I received it. Anyway, if you haven't guessed by now the 130 in the name refers to 130mm of aperture, that's the size of the corrector lens, I can't measure the primary mirror without completely disassembling the tube so I can't easily determine if it's truly a 130mm scope. The focal-ratio is f/15.4 for a focal length of 2000mm (long even for a MCT) folded into a scope only 400mm long and weighing under 4kg, so it rides effortlessly on my SkyView Pro mount and would be eminently usable on lighter mounts. The main tube is metal, painted blue and with a 'Konus Motormax' logo on the side, the logo comes even without the mount, the tube has a dovetail bar secured to it which worked on my mount with no modifications required, and a small dovetail holder for the supplied 10x50 finder scope is secured to the top of the tube. The rear of the tube is almost all plastic and includes a 1.25" eyepiece holder at 90º and a straight through location for the attachment of thread on optical components. A flip mirror system lets you swap quickly between these while observing with little more than an adjustment to the focuser, I was really attracted to this feature since my efforts at imaging planets using a webcam were always hindered by the difficulty in getting the planet into the tiny FOV of the CCD, usually involving swapping back and forth between an eyepiece and the camera while making adjustments to the pointing. It's usually sold as a spotting scope so it comes bundled with a 45º correcting prism that screws onto the back, and for another $25 there's a T-adapter for photography that'll attach to the rear cell. The plastic back showing the focus knob, mirror lever, and eyepiece adapters at 90º and 45º The front of the scope reveals the concave corrector with a bluish tinge from the coatings, the corrector is labelled as 'multi-coated', rather than 'fully-multi-coated', the Maksutov design should only have 2 refracting surfaces in the corrector, so I'm wondering if one of those surfaces is less transmissive than it could be? While I've learned to look for the 'fully-multi-coated' phrase I've been more than happy with the performance of my plain old 'multi-coated' refractor, so I'm sure this'll be no big deal. The front corrector assembly is held in place by a few small screws which supposedly allow adjustment of the alignment, I sincerely hope I never need to touch these. No dew shield was included, I constructed one myself out of sheet plastic and it performed admirably, and for a small sum of cash there are a number of compatible after-market dew shields available. Looking down the scope through the spherical corrector plate. The First Night on a Cheap Date The first night out was a couple of days before full moon with Jupiter in the western sky hovering over my neighbours rooftop and disappearing fast. Even through the turbulent air I could appreciate there was a definite improvement in the view compared to my other scope, no observable chromatic aberration lent the view a 'warmer' feel, or maybe that was just the thermally induced turbulence? It was certainly a more relaxed experience with the focus being found easily and no extra optics being needed, I can't honestly say that I saw any more detail in the giant planet on that night, but it was an easier experience than I was used to. People talk about image shift being an issue, where adjusting the focus can have the side effect of moving the visual field, and this is observable but certainly not an issue, in fact the cheap R&P focuser on my refractor shows similar shift when it has heavy optics attached to it, so no drawbacks there. Turning to the moon however a couple more problems were discovered, firstly I painfully discovered that the finder scope is just too darn close to the 90º eyepiece holder, I managed to poke my left eye with it as I craned my neck around to position my eye, now I have a homemade visual back this isn't a problem any more, but for a moment that was all I cared about. Having figured out how to situate myself and observe the moon I noticed that the scope had slipped out of focus, there's definitely a fair amount of play in the focus and pointing the scope towards zenith apparently causes the main mirror to settle enough that it may need adjustment when slewing the scope around the sky, not a huge adjustment, but enough that you want to make sure you not doing long exposure imaging with it (however, lets face it, anyone who can afford the gear for such long exposures probably isn't doing it through a $200 scope from eBay).   Once focused the moon looks jaw droppingly good, it was well clear of any rooftops and the air was much cleaner, the lowest magnification 1.25" eyepiece I own is a 25mm Plossl providing 80x magnification and a field of view which barely contained the earth's nearest neighbour. I stepped up the magnifications using my limited eyepiece collection and peaked at x222, the next step up would be X333 with a 6mm eyepiece and this was clearly beyond the limits of the optics and seeing, perhaps if I had some eyepiece in the correct range I would find a useful magnification in that untested range. The moon showed up a slight yellowish cast to the optics, no doubt a result of those blue coatings on the front, it's very slight, a lot less than you would see with a minus-V filter,  but it's probably enough to annoy some people. With my small observing time window running out (I had to put my daughter Skye to bed) I headed outside the solar system for some quick optical tests on bright stars, this was a pleasantly uneventful experience with clean diffraction rings and no observable CA, at least everything looked fine and in order to my uncritical eyes, at high magnification the scope easily outperforms my refractor. Happy with my first night, I headed inside and read some of 'The Little Prince' to send Skye to sleep. The 6x10-9 Billion Dollar Scope (Upgrade) After first light, I spent a few hours on weekends making some changes to the back of the scope to adapt it to my requirements, the money I saved up front had to be paid with using a little mechanical effort. The threaded ring on the rear isn't a standard type like those found in most Schmidt-Cassegrains, this is smaller and as far as I can tell the 45º diagonal and T-Adapter are the only things I can get which fit. This has a number of implications, firstly, you're stuck with 1.25" eyepieces, secondly, when using those eyepieces you either have to use the internal flip mirror or the 45º prism, the optical quality of both these devices is severely lacking. I've read about various third parties producing compatible visual backs for the scope, but I have no experience with these and can't make any recommendations, instead I disassembled the diagonal, spent a few dollars on plumbing supplies, and constructed a homemade 2" adapter. The actual light path is smaller than 2", but I needed a 2" adapter for my diagonal and filters, I'm sure if you only wanted a 1.25" adapter you could save a few cents on smaller plumbing supplies. To build my own adapter I disassembled the diagonal for the screw on retaining ring. It fits neatly inside some 2" plumbing supplies and screws onto the back of the relescope. My homemade 2" adapter allows me to use a better quality diagonal in place of the poor quality 45º diagonal which is included. The direct optical path is also covered by a small piece of glass for some bizarre reason, the glass is pretty thick and doesn't appear to feature any anti-reflection coatings so it introduces all sorts of  internal reflections, although many users might not notice since these would be compounded by the 45º prism and therefore only use it on terrestrial targets. I can't really fathom the purpose of this, if it were intended as a seal to avoid dust entering the optical system then why isn't there a similar glass seal covering the other eyepiece socket, or better still why not cover the port into the main tube? It's a simple matter to remove the 3 screws that hold on the plastic back and unscrew the glass seal, and there's a definite improvement in the definition when looking at bright targets, it may be prudent to find a better seal to cover the port into the primary optical cavity. Disassembling the rear of the Konus scope was pretty easy, but I've read some reports which indicate this is one way that the Celestron model differs, people have had to resort to attacking the focus knob with power tools to remove it and then taken a chisel to the glass seal, the simple modification I made may be a lot harder on the Celestron C130. Close up of the rear cell, the thread size is non standard and the glass seal is a thick piece of uncoated glass! To remove the glass seal - first remove the focus knob. Unscrew the 3 screws The back should come off easily. The flip mirror provides a built in diagonal for astronomical viewing To get at the seal you need to make sure you flip the internal mirror out of the way. Unscrew the retaining ring. And the glass seal will come out, say goodbye to some of those nasty internal reflections! While the back is off I should also point out the 3 screws used to align the primary mirror, these are only accessible while the back is off and are secured with loctite to make sure you don't mess around with them by accident, and because the back is off you need to find some way too secure an eyepiece or other collimation tool while you're adjusting things. You're pretty much stuck with the collimation unless you want to void your warranty, so I'm glad that mine came with as close to perfect collimation as I've seen in any scope I've used, even after getting shipped across the country and the box getting a big dent in the packaging the alignment is still spot on. If you're an incorrigible tweaker it's possible to modify the plastic back, either to add externally accessible bolts, or simply drill holes through the plastic to make the screws accessible with the back and optical adapters attached. For the moment I'm not nearly so courageous and while similar scopes provide easier access to adjust the collimation, none of the manufacturers encourage the end user to make such adjustments. The back of the tube proper, the screws and bolts can be used by fearless scope hackers to collimate the primary mirror. New and Improved, But Still Cheap Having eliminated the impediments to performance associated with the plastic back I can report that these are well worth your time, the improvements over the flip mirror or the 45º diagonal bring clearer views and better colour definition, the cheap scope becomes competitive with other scopes and becomes suitable for my original photographic intentions. But curious to see how competitive it was I secured a couple of friends to meet up in a dark field and have a good old cat fight, for comparison we secured a Meade ETX 125 with UHTC coatings and an Orion 102mm StarMax, hardly a fair match, but they should have been glad that my friend with his 14" RCX400 had better things to do. To cut a long story short, the Konus held up well, there was little difference in terms of optical aberrations and the light gathering was better than the smaller Orion, but lagged behind the Meade with its improved coatings, but we have to remember I paid less for mine than either of my friends, so I certainly won points in the 'bang for your buck' stakes. While the comparison wasn't so close it did give me a real chance to confirm that the optics on the Konus were at least as good as those from other companies. So, what kind of views did I get? Well it's time for that telescope review cliché - the list of familiar targets and some comments on how well the instrument wrangled those long travelled photons into my eye. M57 - The Ring Nebula - showed up features I'd never seen when I used a narrowband light pollution filter, by turning my head I could see variations in the shape and brightness of the ring. An extra inch of aperture wasn't nearly enough to let me get a handle on the central star. While I was in the neighborhood I made the traditional pilgrimage to the Lyra's Double-Double for testing a new scope, it easily resolved all of the components, even at the lowest magnification available to me both pairs were easy splits. With M13 I certainly discerned a number of stars which had never been visible in my other scope, a myriad of stellar points resolved themselves out of the fuzzy core, frankly I was amazed by the difference that 1" of aperture made, and perhaps the more focused points made fainter stars easier to resolve. Comet SWAN was nearing closest approach to the Earth and put on a good show with an intensely concentrated coma showing the barest hints of the blue-green colour which photos had shown. Sadly, I couldn't pick out any real evidence of a tail, however the comet's motion against the surrounding stars was apparent at the range of magnifications offered by the scope and eyepieces. M31 - Andromeda - I lacked the aperture to discern anything more than the core, but the steep cutoff in brightness caused by the most prominent dust lane was visible, the magnification was much higher than I'd usually use and I think that made it easier for me to pick out one well known feature, but the miniscule field of view doesn't lend itself to observation of this giant target. M45 - Pleiades - don't bother, forget this cluster in any scope which doesn't have a wide field of view, the stars were all wonderfully resolved but I was glad to have my refractor around to appreciate this classic target. M42 - The Great Nebula in Orion showed far more of the nebular structure than I'd ever seen in my refractor, the extra aperture made a small difference for sure, the four components of the Trapezium were ridculously easy to split, even at the lowest magnification available to me they were all present and correct, I'd like to think I glimpsed one of the fainter Theta components in the cluster. Orion was pretty low in the sky, but I spent a lot of my time on it, comparing the shape of the nebula under different filters and magnifications. No planets were visible from that dark site on that night, but the pressure to give it a go against a planet in good conditions had me up early in the morning before the sky had started to brighten and Saturn was high in the sky, Saturn was magnificent, a joy to behold the air was still and the rings were well defined all the way up to x222 magnification. Talking about the views through a scope is all well and good, but I made a serious attempt at imaging the planet so I could actually show you what can be seen, the seeing wasn't as stable as I'd like, but I'm quite happy with this first attempt. In Summary, pinpoint stars, apo-like chromatic aberration, small aperture and high magnifications make this great for the moon and planets, adequate for bright compact DSO's and completely rubbish for any extended or faint targets. These observations are hardly surprising for a small aperture MCT, my suspicions regarding its near ubiquitous presence on eBay were largely unfounded and the telescope has surpassed those low expectations and proved to have decent optics. The one part that failed to live up to expectations was the flip mirror system which turned out to be inadequate for my purposes, centering a small object in one eyepiece and flipping the mirror will show a significant displacement in the centering, placing a planet in the tiny CCD of the camera still requires a bit of sky scanning to get right. The deflection from centre is similar for both the supplied diagonal and my homemade adapter indicating that it's likely to be a problem with the mirror alignment,  I'm hoping to find a way to adjust this but that may turn out to be a harder task than collimating the primary, so I'm prepared to live with it. The plastic back also has a bit of give to it, this translates to a small amount of flex in the rear cell, If you hang a heavy camera off the back it might be an issue, although the mirror motion is probably comparable in magnitude. Perhaps if you're a real believer in the optics you could discard the plastic back altogether and attach your own adapter to the back of the tube, that way you'd only have to deal with the settling of the primary. Summary: A Great Deal For The Right Buyer That's really the theme for this scope, you may pay half the price of a similar scope from a more reputable manufacturer, but you have to spend a small amount of effort to make it truly competitive. From my point of view I think it was a great buy and tuning the scope up was quite an enjoyable experience in and of  itself, the total cost was $200 (including shipping) for the tube, $5.39 for the plumbing parts and maybe 2 hours of actual work on the adapter and the back of the tube. For me it's a perfect complement to my refractor, for imaging its a logical progression in the range of focal lengths in my collection (205mm, 600mm and now 2000mm), and unlike a long focus refractor/newtonian it rides comfortably on my mount and tracks with enough precision to make DSLR imaging possible. I'll be happy, until the day I can afford something with more aperture. And so, to wrap up, here's the balance sheet Good Points Bad Points Cheap Plastic Back Decent optics in main tube Glass seal and flip mirror are poor Compact and light with a standard dovetail bracket Non Standard thread adapter. Flip Mirror system helps with imaging Collimation is hard. Great on planets Terrible at faint and extended objects. If you're strapped for cash, halfway handy and looking for a planetary scope then this might just be what you're looking for, and if you don't have a mount then the package might be worthy of your consideration and perhaps hard earned cash. However most peoples needs are outside this group and it is a poor choice for a beginners scope it's more of a niche scope, a niche that is as narrow as its field of view. There's an established practise of slapping an Italian name on Chinese manufactured goods, it doesn't magically make them any better. And before anyone asks - if I have another kid, they're not going to be called Konus. Scott Manley, November 2006